The invention relates to the field of omni-directional, planar folded dipole antenna systems operating in defined frequency bands. More particularly, the invention relates to an innovative, low cost omni-directional planar antenna and quadrature phase shifter implemented on separate, perpendicularly engaged printed circuit boards (xe2x80x9cPCBsxe2x80x9d). The invention is particularly useful for short range radio frequency applications such as gaming, consumer electronics and data communications.
Conventional phase shifters require additional electronic circuitry such as power dividers, resistors, inductors and capacitors. These components increase manufacturing cost and reduce system reliability. Consequently, the elimination or reduction of such components would be highly beneficial.
Various planar dipole antennas and antenna systems have been developed. For example, U.S. Pat. No. 3,813,674 to Sidford (1974) described a folded dipole antenna without radiator elements fed by a switched diode mechanism. U.S. Pat. No. 4,083,046 to Kaloi (1978) described a planar monomicrostrip dipole antenna formed on a single side of a dielectric material that was excited in a non-quadrature manner. U.S. Pat. Nos. 4,155,089 and 4,151,532 to Kaloi (1979) described twin electric microstrip dipole antennas consisting of thin electrically conducting patches formed on both sides of a dielectric substrate excited in a non-quadrature manner. U.S. Pat. No. 4,438,437 to Burgmyer (1984) described two monopoles mounted on one side of a PCB and feed lines connected on the opposite side. U.S. Pat. No. 4,916,457 to Foy et al. (1990) described a cross-slotted conductor fed with a quadrature signal employing a multi-layer PCB construction. U.S. Pat. No. 4,973,972 to Huang (1990) described a circularly polarized microstrip array antenna utilizing a honeycomb substrate and a teardrop shaped inter-layer coupling structure.
In other systems, Huang (1990) described a rudimentary phase shifting strip line feed integral to the antenna structure. U.S. Pat. No. 5,481,272 to Yarsunas (1996) described a circularly polarized microcell antenna employing a pair of crossed, non-microstrip dipoles fed through a single feed-line. The phase shifters were integral to the antenna feed design and the entire structure was manually bolted together. U.S. Pat. No. 5,508,710 to Wang et al. (1996) described a planar antenna having a circular folded dipole antenna. U.S. Pat. No. 5,539,414 to Keen (1996) and U.S. Pat. No. 5,821,902 to Keen (2000) described a single element folded dipole microstrip antenna fed by a coaxial cable. U.S. Pat. No. 5,592,182 to Yao et al. (1997) described a non-PCB dual-loop omni-directional antenna that was driven in phase quadrature. U.S. Pat. No. 6,057,803 to Kane et al. (2000) described hybrid combinations of planar antenna elements.
U.S. Pat. No. 5,268,701 to Smith et al. (1993) described a dual polarized antenna element composed of two perpendicular inter-locking elements where both the antenna and phase shifting sub-elements were incorporated into multiple layers of each sub-element so that the antenna and the phase shifting circuitry were both mounted on expensive sub-elements.
U.S. Pat. No. 5,628,057 to Phillips et al. (1997) described a strip line transformation network capable of interfacing between an unbalanced port and a plurality of differently phased balanced ports using variable length strip lines and interconnecting vias between layers. U.S. Pat. No. 5,832,376 to Henderson et al. (1998) shows a hybrid RF mixer/phase shifter containing both stripline and electronic components such as diodes.
Despite the variety of systems providing an antenna for use with electronic components, a need exists for an improved antenna system providing superior manufacturing and operating efficiencies.
The invention provides a planar, omni-directional antenna system for use with printed circuit boards. The system comprises a planar antenna engaged with a first printed circuit board for radiating and receiving electromagnetic signals, wherein the antenna has four quarter-wavelength, folded dipole sections organized in pairs, at least one pair of phasor passive radiator elements associated with said folded dipole sections on the planar antenna, a radio frequency transceiver, a quadrature phase shifter circuit engaged with a second printed circuit board wherein the quadruture phase shifter circuit comprises a phase shifting hybrid power divider and transformer connected to the planar antenna and the radio frequency transceiver, and at least one connector trace connecting the planar antenna, quadrature phase shifter, and radio frequency transceiver.